Electrical selective system



June 24, 1 9249 k c. B. FOWLE,

ELECTRICAL SELECTIVE SYSTmE Filed March 9. 1 920 Patented June 24, 1924.

CLARENCE B. FOWLER, OF NEW YORK, N. Y., ASSIGNOR TQ WESTERN ELECTRICCOM- PANY, INCORPORATED, 01 NEW YORK, N. Y., CORPORATION OF NEW YORK.

ELECTRICAL SELECTIVE SYSTEM.

Application filed March 9, 1920. I Serial No. 864,553.

To all whom it may concern.

Be it known that I, Cmnnnon B. FOWLER, a. citizen of the United States,residin at New" York, in the county of New York, State of New York, haveinvented certain new and useful Improvements in Electrical SelectiveSystems, of which the follow ing is a full, clear, concise, and exactdescription.

This invention relates to electrical selective systems and moreparticularly to electrical selective systems for use in automatic orsemi-automatic telephone exchange systems.

One of the objects of this invention is to provide in a system of thisnature, a number indicating device adapted to be set under the controlof an impulse sender and retained in its set position until released.

A further object of this invention is to provide an improved impulsecircuit for controlling switches.

In accordance with one of the features of this invention a plurality ofstep-'by-step switches are adapted to be successively set in responsetothe sending of a plurality of series of impulses from a common implusetransmitting means. A plurality of signals, preferablty one for eachdigit of the decimal system 0 notation are associated with each switch.In response and corresponding to the impulses transmitted by the impulsetransmitting means, signals are actuated. Actuation of a key returns allthe switches to ngrmal, thereby deenergizing the signals.

Another feature of the invention, while employed in this invention butnot necessarily limited thereto, consists in interposing a quick-actingrelay between an impulse relay and a slow-acting relay usually emloyedin connection with a selector switch or controlling an auxiliary switchor side switch associated with the selector switch.

The purpose of this nick-acting relay is to insure actuation of te-auxiliary swltch at the proper'time;

For a 'more complete understanding of this invention, reference maybemade to.

the operation of selectori well-known type of step-by-step switcli, as

ior example that shown in the U. S.

ent No. 1,472,465 of Forsberg and deVignier, issued October 30, 1923. Inthe particular system shown, each switch may be provided with three setsof contact banks. For the purpose of this specification the lower,middle, and upper contact banks will be termed, restoring, switching andsteering banks respectively. The brushes of the steer ing banks areslightly different from those of the restoring and switching banks inthat they are. of the bridging type, that is, the brushesmake-before-break in passing from one contact to thenext. To. eachsteering bank are connected, a plurality of signals preferabl one foreach digit of the decimal system 0 notation; through each switching.bank an auxiliary. switching device, such as relay 31., is controlled;-and through each restoring bank, an operating circuit for restoring theswitches to normal is controlled.

Each switch is provided with a motor magnet, M, M such as 30'; whichoperates under the control of the impulse sender to move its associatedbrushes such as 32, 33'

and 34. The motor magnet 30 first operates to control the signalcorresponding to the I digit dialed and subsequently operates to restorethe switch to normal.

Each auxiliary switch, herein shown as a' relay, such as 31, operates atthe-end of each series of impulses to connect an impulse circuit to thesucceeding switch. The actuation of relay 31 is controlled byslowto-relea'se relay 24, which is energized during the sending ofimpulses, and a quickacting relay 23, which operates in response to thefirst interruption of the impulse circuit to operate 'slow-to-rcleaserelay 24. Relay 31 is thus initially prevented from operating during thesending of each series of impulses b subsequent y by relay 24.

The nature of the invention is such that it is believed a clearerunderstanding thereof will be obtained from a description of theoperation of the system shown and it will be so described.

It will be assumed, for thepurpose of illustration, that an operatorhaving. access to a sender S desires to dial the number 2345. Havingassociated the sender'with the impulse relay 20, in anyiwell-knownmanner as by operating a key or inserting a plug the operation of relay23 and in a jack (not shown but schematically indicated by'the contacts10),'relay 20, and 1n turn slow-to-release relay 21, are operated. Theoperator then proceeds to send out impulses in accordance with thedesired num-' ber. Assuming that the sender S is of the well-knownrotary or dial type, 'two interruptions of the circuit for relay 20 willoccur when digit,2 is dialed. Upon the first interruption of thecontacts 18 of the sender S, the circuit forv relay 20 is opened and ed;battery. Magnet 30 in actuating moves the brushes of switch A. one stepinto engage'ment'with its first set of contacts. Re,- lay 23 inenergizing completes a lockin circuit for itself and causes ground to bep aced on conductor 19, extending through the lower normal contacts ofrelay 31 to the strapped terminals of the switching bank 33 of switch A,thusshort-circuiting relay 31 and preventing its energization at thismoment. This ground is supplied to conductor 19 through the outer rigt-hand contact of relay 26, the inner make contact of relay 23 and theleft-hand normal contacts of relay 24, until relay 24 operates,whereupon this ground is supplied to conductor 19 through the left-handalternate contacts of relay 24. The locking circuit for relay 23includes the outer right-hand contacts of re lay 26, upper make contactsof relay 23, left-hand winding of relay 23, and the righthandcontact ofrelay 24. Relay 23 in energizing'a'lso completes a circuit for theenergization of slow-to-release relay 24 which,

in energizing, maintains the ground on conductor 19 during the sendingof each series of impulses. The circuit for the energizetion of relay 24may be traced as follows: grounded battery, winding of relay 24, lowermake-contacts of" relay 23, and outer right-hand armature and backcontact of relay 26 to ground. In energizing, relay 24 opens the lockingcircuit for relay 23, thus insuring the immediate release of rela 24,when the impulses of each set cease. rdi- 'narily a-slow-to-releaserelay, such as 24,

which remains energized during the sending of the impulses and releasesat the end of each series of impulses, is used to control the actuationof the -magnet for the side switch or switching device. lit has beenneeaeca demonstrated that while relay 24 is essentially aslow-to-release relay, it is also somewhat slow-to-operate and if theimpulses transmitted are not exact in character, relay 24 is apt not tofunction properly to control the actuation of the switching device (inthis instance relay 31) associated with the selector switch;quick-acting relay 23 is, therefore, interposed between the impulserelay 20 and the slow-to-release relay 24. Upon the first interruptionat the sender, relay 23 operates to control the actuation of relay 31,the control being subsequently transferred to the slow-to-release relay24. At the secondinterruption of the circuit for relay 24, relay 20again deenergizes in response to which motor magnet 30 is againactuated, thus moving the brushes 32, 33 and 34 a second step.

Following-the second interruption of the contacts at the sender S, relay20 again energizes and since the dial has now returned to normalposition, relay 20 is maintained energized for an appreciable time bruntil the operator has set the dial for the second digit. During thisinterval, relay 24 deenergizes thereby removing the ground fromconductor 19 and permitting'the operation of relay 31 over a circuitextending from ground, winding of relay 31, brush 33, strapped contactsof the switching bank and resistance 35 to, grounded battery. Relay 31in operating disconnects the impulse con ductor 29 from ma net 30 andconnects it to magnet 40. The rushes of switch A remain upon thecontacts to which they have been moved, and lamp 2 corresponding to thedigit dialed is caused to glow over a circuit extending from groundedbattery, contacts of key 27, left-hand normal contacts of rela 26,conductor 17, lamp 2, third contact of t e steering bank of switch A,and brush 34 to ground.

From the fore oing it is apparent-that the switches B. and D may besuccessively operated in a similar manner to indi cate the severaldigits, namely, 3, 4, and 5 dialed by the operator and thus anindication (2345) is set up in the bank of lamps corresponding to thedigits dialed.

'lo extinguish the signals and return the switches to normal, restoringkey 27 may be actuated whereupon all switches are simultaneously startedin their movement to normal position. Actuation of non-locking key 27,removes the shunt from relay 26, thereby completing a 'circuit extendingfrom grounded battery, through the winding of relay 26, conductor .17,lamp 2, third contact and brush 34 of switch A 'to ground. Parallelclrcuits to ground extending from conductor 17 through the remainingactuated signals and their associated contacts and brushes are mantained until all switches have reached their normal position. Relay 26is enerstoring bank of each switch for the, motor magnet of each switch.Under the control of their respective motor magnets, the brushes of eachswitch are returned to normal position. the circuit for relay 26 isopened, whereupon relay 26 releases its armatures and the system isready for the next operation.

What'is claimgd is:

1. In an electrical selective system, a num- *ber indicating devicecomprising a plurality of sets of signals, each set having one signalfor each digit of the decimal system of notation, a train of switches,one for each set of signals, means for actuating certain of said signalswhen said switches are in their set positions, means including animpulse sender for sending a plurality of sets of impulses for settinsaid switches, an auxiliary switching evioe individual to each switch ofthe train, and means for successively actuating said auxiliary switchingdevices during the intervals between sets of impulses to associate theimpulse sender with the succeeding switch of the train.

2. In an electrical selective system, a number indicatin devicecomprising a plurality of sets 0 signals, each set having one-signal foreach digit of the decimal":

system of notation, a train of switches, one for each set or signals,means to actuate certain of said signals when said switches are in theirset positions, .means including an impulse sender for sending aplurality of sets of impulses to set said switches, a relay whereby saidrelay is actuated at the cessation of the set of impulses 'for theswitch being set and means whereby said relay when energized associatesthe impulse sender with the succeedin switch of the train.

3. In an electricalselective system, a -num-' ber indicating devicecomprising a plurality of sets of signals, each sethaving one signal foreach digit of the decimal system of notation, a train of switches, onefor each set of signals, means efiective when said switches are in theirset position to actuate certain of said signals, means including animpulse sender for sending a plurality of sets of impulses to set saidswitches, a relay associated with eachswitch of the train, meansefi'ective upon the cessation of eachset of impulses to energize therelay of the switch being set, means whereby said relay upon energizingassociates the impulse sender with t e succeedin switch of the train, anmpulse relay, ant? means including a quick and slow acting relayassociated with said mpulse relay for preventing 'the energizatlon ofthe'relay of the switch being set during the sending of a set ofimpulses.

4. In an electrical selective system, a number indicating devicecomprising a pluralityv In reaching normal, position of sets of signals,each set having one signal for each digit of the decimal system ofnotation, a train of switches, one for each set of signals, means toactuate certain of said signals when said switches are in their setositions, means including an impulse sender or sending a plurality ofsets of im ulses to set said switches, a relay associate with Y eachswitch of the train, means whereby the energization of said relayassociates the impulse sender with the succeeding switch of the train ashunt circuit for said relay, completed upon the initial step of theswitch being operated, and means for removing said shunt when saidswitch has been set to energize said relay to associate the impulsesender with the succeeding switch of the train.

5. In an electrical selective system, a number indicating devicecomprising a plurality of sets of si nals, each set having one signalfor each di it of the decimal system of notation, a tram of switches,one for each setof signals, means including an impulse sender forsending a plurality ofsets of impulses to set said switches, means toactuate certain of said signals corresponding to the set positions ofthe switches, a relay associated with each switch of the train, meanswhereby said relay upon energization associates the impulse sender withthe successive switch of the train and means effective acting relayassociated with said impulse reindividual to each switch of the tram,means 1 av for preventing the ener ization of the relay of the switchbeing set uring the sending of a set of im uses, a release circuit foreach of said switc es, and means for simultaneously closing .all of saidrelease circuits. 6. In an. electrical selective system, an automatic.switch, a stepping ma net therefor, an auxiliary switch associate withsaid automatic switch, means including an impulse relay for transmittinga series of impulses to said stegping magnet, and a quickacting relay ana slow-acting relay associated with said impulse relay for jointlycontrolling the actuation of said auxiliary switch.

7 In an electrical selective system, an automatic switch, meansincludingan impulse relay for controllin said switch, a switchin device associatewith said auto matic switch, a slow-acting relay associated with saidimpulse relay for controlling the 8. In an electrical selective system,an impulse sender, an lmpulse relay responsive vice until saidslow-acting relay is energ zed.

to a Series of impulses from said sender, an automatic switch controlledby said impulse relay, a switching device associated with said switch, aslow-acting relay, means whereby the energization of said slow actingrelay operates said switching device, a quick-- acting relay energizedin response to the first impulse of the series to said impulse relay forenergizing said slow-acting relay and means for deenergizing said slowacting relay to operate said switching device.

9. In an electrical selective system, an automatic switch, a steppingmagnet therefor, means including an impulse relay for transmitting aseries of impulses to said I stepping magnet, a switching deviceassociated with said switch, a slow-acting relay associated with saidimpulse relay energized during the sending of a series of impulses auddeenergized at the end of a series of impulses, a quick-acting relayassociated with saidfimpulse relay responsive to the first impulse of aseries of energizing said slow-acting relay, and circuit connectionscontrolled jointly by said quick-acting relay and said slow-acting relayfor controlling the actuation of said switching device.

In witness whereof, I hereunto subscribe my name this 5th day of MarchA. I1, 1920.

GLARENCE B. FQVVLER.

